/**
	The missing SVG.toDataURL library for your SVG elements
	
	SVG.toDataURL( [type], [keepNonSafe=false], [keepOutsideViewport=false] )

	type	MIME type of the exported data.
			Default: image/svg+xml.
			Must support: image/png.
	
	[the rest of the parameters only apply when exportin image/png (or other non-svg)]

	keepNonSafe
		Export non-safe (image and foreignObject) elements.
		This will set the Canvas origin-clean property to false, if this data is transferred to Canvas.
		Default: false (to keep origin-clean true).

	keepOutsideViewport
		Export all drawn content, even if not visible.
		Default: false, export only visible viewport, similar to Canvas toDataURL().
		
	IMPLEMENTATION NOTES
	
	keepNonSafe and keepOutsideViewport are not supported at all and will be ignored.
	
	if you don't have canvg, a client-side hack¹ is attempted, 
	but this will fail on all current browsers (as of 2010-08)
	
	¹ http://svgopen.org/2010/papers/62-From_SVG_to_Canvas_and_Back/#svg_to_canvas
*/

SVGElement.prototype.toDataURL = function(type, keepNonSafe, keepOutsideViewport) {
	var _svg = this;
	
	function debug(s) {
		console.log("SVG.toDataURL: " + s);
	}

	function exportSVG() {
		var svg_xml = XMLSerialize(_svg);
		var svg_dataurl = base64dataURLencode(svg_xml);
		return svg_dataurl;
	}

	function XMLSerialize(svg) {

		// quick-n-serialize an SVG dom, needed for IE9 where there's no XMLSerializer nor SVG.xml
		// s: SVG dom, which is the <svg> elemennt
		function XMLSerializerForIE(s) {
			var out = "";
			
			out += "<" + s.nodeName;
			for (var n = 0; n < s.attributes.length; n++) {
				out += " " + s.attributes[n].name + "=" + "'" + s.attributes[n].value + "'";
			}
			
			if (s.hasChildNodes()) {
				out += ">\n";

				for (var n = 0; n < s.childNodes.length; n++) {
					out += XMLSerializerForIE(s.childNodes[n]);
				}

				out += "</" + s.nodeName + ">" + "\n";

			} else out += " />\n";

			return out;
		}

		
		if (window.XMLSerializer) {
			debug("using standard XMLSerializer.serializeToString")
			return (new XMLSerializer()).serializeToString(svg);
		} else {
			debug("using custom XMLSerializerForIE")
			return XMLSerializerForIE(svg);
		}
	
	}


	var Base64 = {

		// private property
		_keyStr : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",

		// public method for encoding
		encode : function (input) {
			var output = "";
			var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
			var i = 0;

			input = Base64._utf8_encode(input);

			while (i < input.length) {

				chr1 = input.charCodeAt(i++);
				chr2 = input.charCodeAt(i++);
				chr3 = input.charCodeAt(i++);

				enc1 = chr1 >> 2;
				enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
				enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
				enc4 = chr3 & 63;

				if (isNaN(chr2)) {
					enc3 = enc4 = 64;
				} else if (isNaN(chr3)) {
					enc4 = 64;
				}

				output = output +
				this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) +
				this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4);

			}

			return output;
		},

		// public method for decoding
		decode : function (input) {
			var output = "";
			var chr1, chr2, chr3;
			var enc1, enc2, enc3, enc4;
			var i = 0;

			input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

			while (i < input.length) {

				enc1 = this._keyStr.indexOf(input.charAt(i++));
				enc2 = this._keyStr.indexOf(input.charAt(i++));
				enc3 = this._keyStr.indexOf(input.charAt(i++));
				enc4 = this._keyStr.indexOf(input.charAt(i++));

				chr1 = (enc1 << 2) | (enc2 >> 4);
				chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
				chr3 = ((enc3 & 3) << 6) | enc4;

				output = output + String.fromCharCode(chr1);

				if (enc3 != 64) {
					output = output + String.fromCharCode(chr2);
				}
				if (enc4 != 64) {
					output = output + String.fromCharCode(chr3);
				}

			}

			output = Base64._utf8_decode(output);

			return output;

		},

		// private method for UTF-8 encoding
		_utf8_encode : function (string) {
			string = string.replace(/\r\n/g,"\n");
			var utftext = "";

			for (var n = 0; n < string.length; n++) {

				var c = string.charCodeAt(n);

				if (c < 128) {
					utftext += String.fromCharCode(c);
				}
				else if((c > 127) && (c < 2048)) {
					utftext += String.fromCharCode((c >> 6) | 192);
					utftext += String.fromCharCode((c & 63) | 128);
				}
				else {
					utftext += String.fromCharCode((c >> 12) | 224);
					utftext += String.fromCharCode(((c >> 6) & 63) | 128);
					utftext += String.fromCharCode((c & 63) | 128);
				}

			}

			return utftext;
		},

		// private method for UTF-8 decoding
		_utf8_decode : function (utftext) {
			var string = "";
			var i = 0;
			var c = c1 = c2 = 0;

			while ( i < utftext.length ) {

				c = utftext.charCodeAt(i);

				if (c < 128) {
					string += String.fromCharCode(c);
					i++;
				}
				else if((c > 191) && (c < 224)) {
					c2 = utftext.charCodeAt(i+1);
					string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
					i += 2;
				}
				else {
					c2 = utftext.charCodeAt(i+1);
					c3 = utftext.charCodeAt(i+2);
					string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
					i += 3;
				}

			}

			return string;
		}

	}
	
	function base64dataURLencode(s) {
		var b64 = "data:image/svg+xml;base64,";

		if (window.btoa) {
			debug("using btoa for base64 encoding");
			b64 += btoa(s);
		} else {
			debug("using custom base64 encoding");
			b64 += Base64.encode(s);
		}
		
		return b64;
	}
	
	// WON'T WORK; canvas' origin-clean is dirty
	function exportPNG() {
		var canvas = document.createElement("canvas");
		var ctx = canvas.getContext('2d');
		var img = new Image();
		var svg_xml = XMLSerialize(_svg);
		img.src = base64dataURLencode(svg_xml);

		img.onload = function() {
			ctx.drawImage(img, 0, 0);
			// SECURITY_ERR WILL HAPPEN NOW
			var png_dataurl = canvas.toDataURL();
			callback(png_dataurl);
		}
		
		img.onerror = function() {
			console.log(
				"Can't export! Maybe your browser doesn't support " +
				"SVG in img element or SVG input for Canvas drawImage?\n" +
				"http://en.wikipedia.org/wiki/SVG#Native_support"
			);
		}

		// TODO: will not return anything
	}

	function exportPNGcanvg() {
		var canvas = document.createElement("canvas");
		var ctx = canvas.getContext('2d');

		// TODO: canvg issue don't require parentNode
		canvas.setAttribute("style", "display: none;");
		document.body.appendChild(canvas);

		var svg_xml = XMLSerialize(_svg);

		canvg(canvas, svg_xml, { ignoreMouse: true, ignoreAnimation: true });
		var png_dataurl = canvas.toDataURL();
		document.body.removeChild(canvas);

		return png_dataurl;
	}

	// BEGIN MAIN

	if (!type) type = "image/svg+xml";

	if (keepOutsideViewport) debug("keepOutsideViewport NOT supported and will be ignored!");
	if (keepNonSafe) debug("keepNonSafe is NOT supported and will be ignored!");
	
	switch (type) {
		case "image/svg+xml":
			return exportSVG(this);
			break;

		case "image/png":

			if (window.canvg) {
				debug("Using canvg for png exporting")
				return exportPNGcanvg(this);
			} else {
				debug("Sorry! You don't have canvg. Using native hack for png exporting, THIS WILL FAIL!")
				return exportPNG(this);
			}

			break;

		default:
			debug("Sorry! Exporting as \"" + type + "\" is not supported!")
	}
}